1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device, and in particular, relates to a method for forming a pattern of a conductive layer, a semiconductor layer, or the like.
2. Description of the Related Art
Conventionally, a large number of thin films such as an insulating layer and a conductive layer are formed over a substrate and a lithography technique is appropriately used to manufacture a MOS transistor, a thin film transistor (hereinafter also referred to as a TFT), and a semiconductor device including such a transistor. A lithography technique is a technique in which a pattern of a circuit or the like called a photomask, which is formed using a light-blocking material over a transparent flat plate, is transferred to an aimed object by utilizing light. The lithography technique is widely used in a process of manufacturing a semiconductor integrated circuit and the like.
The manufacturing process using a lithography technique requires multiple steps such as resist application using a photosensitive resin called a photoresist, light exposure, development, etching using a resist as a mask, and resist removal. Therefore, the throughput is inevitably decreased as the number of lithography processes is increased.
For example, a technique for processing a pattern into a linear shape without using a photoresist is proposed in Patent Document 1 (Japanese Published Patent Application No. S63-84789). Patent Document 1 describes a technique in which a transparent conductive film (ITO) is linearly irradiated with an excimer laser beam to form a linear opening, so that a pattern is formed.
In addition, Patent Document 2 (Japanese Published Patent Application No. 2005-099500) describes a technique, in which a resist including aliphatic polyester is used; and the resist is selectively exposed to ultraviolet ray so that the resist in the ultraviolet-irradiated region is removed, thereby making a development step using a developing solution unnecessary and simplifying the lithography process.